Subcaliber rifle barrel with slidable cap member for holding a subcaliber cartridge



3,334,603 EMBER O. EDSTRGM Jan. 23, 1968 SUBCALIBER RIFLE BARREL WITH SLlIJABLE CAP M FOR HOLDING A SUBCAIJIBER CARTRIDGE Filed June 16, 1966 l 1 I I I INVENTOR E05 fwd/w OLLE ATTORNEYS United States Patent Ofitice 3,364,608 Patented Jan. 23, 1968 ABSTRACT OF THE DISCLOSURE A device for adapting a rifle to receive and fire subcaliber cartridges, the device comprising a subcaliber barrel snugly and adjustably receivable into the breech end of the rifle barrel, and a cap member slideably mounted upon the breech end of the subcaliber barrel and adapted to hold the subcaliber cartridge in firing position.

When practising shooting indoors, for example, with rifles, it is a common thing to arrange an insertion barrel in the rifle barrel in this manner to adapt the rifle to practice ammunition of a small caliber. However, the arrangement of such an insertion barrel involves certain practical drawbacks. Inter alia the bore of the rifle may be damaged, and moreover the shooting conditions will not be equivalent to the conditions prevailing when normal ammunition is used owing to the fact that it is not possible to place a number of shots in the cartridge magazine. This involves relatively tedious reloading between the shots. It has been proposed to arrange a bushing or lining with a configuration and dimensions essentially conforming to a cartridge normal for the arms in question, the cavity of the bushing being formed into a rifle bore and the rear end of the bushing in the shooting direction being provided to receive a small caliber cartridge.

The systems described above :are often used for practising shooting and partly satisfy the demands that can be made in respect of such equipment. However, in practising precision shooting it has been proved that such systems do not achieve the desirable accuracy of aim, since it is difficult to obtain correct aiming with an insertion tube no longer than a normal cartridge. The guidance in the rifle bore is, in fact, greatly dependent on the length of the insertion tube. In case a long insertion tube is used it is very awkward to be forced for every reloading to pull the insertion tube out of position in the rifle bore and cartridge chamber, and moreover the rifle bore may easily be damaged during such operations. In order to eliminate the said drawbacks an arrangement has also been proposed, in which the rear portion of the insertion tube is made as a separate, removable member provided to receive a practice cartridge and to cooperate with the bolt of the firearm. An arrangement of the said kind is, for example, set forth in the US. Patent 1,538,561. The present invention relates to such a type of insertion tubes, in which the portion containing the bore will constantly remain in the cartridge chamber and the rifle bore during the shooting exercise. The problem with the latter insertion tubes is accurately to insert them to the respective cartridge chamber in a firearm. In order to achieve good accuracy of aim with such a system it is of great importance that the insertion tube remains in a well fixed position in the cartridge chamber during the period of the shooting exercise. In practice it has been proved that the cartridge chambers may differ more than .1 mm. in dimensions in different rifles. The present invention hasfor its object an arrangement with which an insertion tube can be adapted to cartridge chambers within large tolerance zones.

The invention is characterized in that the portion of the arrangement disposed within the cartridge chamber zone has a smaller diameter than the interior diameter of the cartridge chamber and is provided with a thread, around which a nut is arranged, the outer surface of which is tapered for fitting into the cartridge chamber of the firearm.

The present invention will be described more in detail hereinafter with reference to the accompanying drawing, in which FIG. 1 illustnates an embodiment of the invention in a longitudinal section,

FIG. 2 shows the same insertion into a rifle, and

FIG. 3 shows the same arranged in an operating position.

The arrangement illustrated in FIG. 1 comprises a bushing 1, the shape of which substantially corresponds to a cartridge normal for the respective rifle, and which is provided with an extension 2 at the front. The bushing 1 has a passage right through in the shape of a bore 3 running centrally through the bushing and its extension. The rear portion 4 of the bushing 1 in the shooting direction is tapered to a smaller diameter and partly provided with a thread 5. On the free end 4' of the said portion 4 is removably disposed a back piece or cap 6 shaped as the rear portion of a normal cartridge and provided to cooperate with the bolt of the rifle, the back piece being provided with a bore 6 to fit the said free end 4. The jacket face of the back piece may be slightly conical. The said back piece 6 is provided with a bore to receive a small caliber practice cartridge 7 with a shot or projectile 8. To adjust the bushing to the cartridge chamber or breech of the firearm a nut or sleeve 9 having a conical jacket face is placed on the threaded portion, it being possible to screw the nut to fit the cartridge chamber of the respective firearm tightly to bear on the walls of the cartridge chamber, which walls generally are slightly tapering.

The arrangement operates in the following way.

Before any shooting can take place, the bushing 1 with its extension 2 is inserted in the cartridge chamber of the rifle bore as seen in FIG. 2, the not 9 then being screwed to the best fitting with the back piece 6, so that it comes into the intended cooperating position with the insertion tube 1, see FIGS. 1 and 2, for shooting after pushing forward the bolt of the firearm. The nut may be turned with any suitable special tool, for example a screwdriver with a bore for the free end 4' for the insertion tube, the nut being provided with a cooperating groove. Naturally the bolt of the firearm must be pulled out when operating the nut in this manner. When pulling out the bolt of the firearm, FIG. 3, the back piece 6 will be pulled out, which can then be exchanged like an ordinary cartridge and a new cartridge 7 be inserted in the back piece and the latter be replaced in the actuating mechanism of the firearm. When the bolt is pushed forward the striking pin is set and the shooting can take place.

The advantage of the arrangement according to the present invention is the fact that the relatively long bore 3 of the bushing 1 will be very accurately fixed in relation to the bore of the rifle, the total said arrangement once fixed remaining in the cartridge chamber during the entire shooting exercise. The back piece 6 with its cartridge 7 will in this way not damage the cartridge chamber during repeated exchanges, neither the rifle bore, while the accuracy of aim is greatly improved.

What is claimed is:

1. A device for adapting a rifle to fire the projectile from the suboaliber cartridge, said rifle having a barrel 3 4 with a cartridge receiving breech at its rear end and a engageable with the Wall defining the breech of the mechanism for extracting the cartridge from the breech, rifie barrel; and comprising: a cap member having a concentric bore adapted to hold an elongated, tubular member slideably and snugly resaid subcaliber cartridge, said bore having an enceivable into the rear end of the rifle barrel, the inter- 5 larged portion adapted to slideably receive the rear nal diameter of the tubular member being adapted to end of said tubular member, said cap member having guide the projectile of the subcaliber cartridge, said an annular groove engageable by the extracting tubular member having an enlarged, substantially mechanism of the rifle for removing said cap and said cylindrical portion for limiting frontward movement subcaliber cartridge from said tubular member. of said tubular member with respect to said breech, 10 and said tubular member having a threaded external References Cited surface between said enlarged cylindrical portion and UNITED STATES PATENTS g sp from the rear end of i tubular 732,540 6/1903 Garrison 4247 sleeve means having a slightly tapered outer surface 15 FOREIGN PATENTS and a threaded inner surface threadedly engageable 103,242 2/1924 Switzerland with the threaded portion of said tubular member, the outer surface of said sleeve means being firmly BENJAMIN BORCHELT: Prima'y Examinen 

